Abstract
Bay scallops (Argopecten irradians) are an economically valuable species whose populations have declined in recent decades due in part to harmful algal and cyanobacterial blooms. Nantucket, Massachusetts hosts one of the last remaining bay scallop fisheries in the U.S., but recently documented the occurrence of a non-native cyanobacterium (Hydrocoleum sp.). Hydrocoleum can form dense mats in seagrass beds, the primary habitat of scallops, but is also diazotrophic, potentially augmenting bioavailable nitrogen to primary producers and fueling secondary production. We conducted surveys to explore the relationships between Hydrocoleum and scallop condition, reproductive potential, and density in eelgrass beds in Nantucket Harbor as well as effects of other habitat characteristics (e.g., eelgrass cover) on these same scallop traits. We found low Hydrocoleum cover during our sampling, but found fewer large scallops in plots with Hydrocoleum, suggesting that this size class may be especially vulnerable to negative effects of Hydrocoleum. Contrary to expectation, we found a positive correlation between Hydrocoleum cover and scallop condition. These patterns suggest that Hydrocoleum may enhance scallop condition, but also affect habitat use, highlighting the need for manipulative experiments to clarify mechanisms driving these relationships. Understanding how non-native species such as Hydrocoleum impact fishery species will help advance conservation and resource management efforts.
•Non-native cyanobacterial blooms can affect performance of commercially-important native species.•A non-native cyanobacterium, Hydrocoleum sp., is becoming abundant in Nantucket, Massachusetts.•We conducted field surveys on Nantucket to quantify the effect of Hydrocoleum on bay scallops (Argopecten irradians).•We found fewer large scallops in plots with Hydrocoleum, but Hydrocoleum was positively associated with scallop condition.•This is the first report on the relationship between Hydrocoleum and bay scallops in the literature.